Classify each molecule as polar or nonpolar.
Here, we are going to classify the given molecules as polar or nonpolar..
In case of heteronuclear molecules(containing different atoms), the shared electron pair between the two atoms gets displaced more towards the more electronegative atom. The resultant covalent bond is called polar covalent bond.
As a result of polarisation, the molecule possesses the dipole moment which can be defined as the product of the magnitude of the charge and the distance between the centres of positive and negative charge. Further, dipole moment is depicted by a small arrow with tail on the positive centre and head pointing towards negative centre.
On the other hand, when covalent bond is formed between two similar atoms, for example, in H2, O2, Cl2 or N2, the shared pair of electron is equally attracted by the two atoms. As a result, the electron pair is situated exactly in between the two identical nuclei. The bond so formed is called nonpolar covalent bond.
The structure of BH3 molecule is given below:
BH3 molecule, as we can see has a symmetrical arrangement of atoms. Due to this symmetrical arrangement in the molecule, no region of unequal sharing arises.Hence, the molecule is nonpolar.
The structure of CHCl3 molecule is given below:
CHCl3 molecule, as we can see has an unsymmetrical arrangement of atoms. It contains one C-H bond and three C-Cl bonds. Here, the C-Cl bond is polar as chlorine is more electronegative. As a result of this unsymmetrical arrangement, a region of unequal sharing arises.Hence, the molecule is polar.